Antarctic Peninsula

ESA's Envisat spacecraft acquired this image on 18 March 2002 using the ASAR instrument in the Wide Swath Mode. The image displays an area covering almost the entire Antarctic Peninsula. This region has experienced exceptional atmospheric warming since the 1950s and is a key area for global environmental research. Over the last 50 years, climate-monitoring stations on the Peninsula have recorded an average temperature increase of 2.5C. Since the early 1980s, surface melting has increased significantly on the ice shelves of the western and northeastern sections of the Peninsula. This has led to the formation of melt-water ponds, weakening the structure of the ice fabric and producing crevasses and rifts. The warming has triggered the retreat and break-up of several ice shelves, culminating in the collapse of the two northern parts of the Larsen Ice Shelf in January 1995 (Larsen A) and in March 2002 (Larsen B). To-date, the open water has reached the rock cliffs of the peninsula, in contrast to January 1995 when the edge of the shelf was 100 km further to the east. Clearly visible in the image is the completely disintegrated ice shelf. The collapsed ice has fractured into thousands of small icebergs and chunks in the Weddell Sea. This kind of ice shelf break-up is quite different from the periodic calving processes that produce large icebergs, such as those visible to the east of Larsen B. These icebergs originated 1000 km further south, at the Ronne Ice Shelf, in 2000. During the retreat and collapse of Larsen B, an area measuring 3300 square kilometers was lost, according to an ESA analysis of the image. Overall, the area of the Larsen Ice Shelf north of Jason Peninsula has decreased from 15 500 square kilometers in 1986, to the 4500 square kilometers remaining today. Climate observations, along with studies of ice dynamics and mass fluxes, indicate that a colder climate would have to persist for several hundred years in order to rebuild the ice shelf completely. Presently, the large ice shelf section, Larsen-C immediately to the south, appears to have been little affected by climate change. However, if warming continues, this ice mass can be expected to recede as well. Envisat's ASAR will serve as a key instrument for observing the extent and dynamics of ice shelves, important indicators of climate change in polar regions. The sensor will make regular observations and enable detailed studies of extent, surface motion and surface melt for Larsen C and all other ice shelves around Antarctica. These measurements will be possible even during the adverse weather and darkness of winter, and are essential to understand ice dynamics and ice/climate interactions. Because ice shelves play an important role in the production of deep water in the Weddell Sea, these observations will also be critical in the study of global ocean circulation.